#include<bits/stdc++.h>
using namespace std;
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
const int N=2e5+10;
#define INF 0x3f3f3f3f;
const int esp=1e-6;
typedef long long int ll;
//#define close(); std::ios::sync_with_stdio(false);cin.tie(0),cout.tie(0);
//----------------------------------------------------------------------------//
int x,l,r;
int main()
{
	//close();
	cin>>x;
	cin>>l>>r;

	double ans=0;
	if(x>r)
	{
		cout<<1.0<<'\n';
	}
	else if(x<=l)
	{
		cout<<0.0<<'\n';
	}
	else
	{
		 
		printf("%lf",(x-l)*1.0/(r-l+1));
	}
	return 0;
}